Hybrid vehicle having multi-mode controller

ABSTRACT

A control system for a hybrid vehicle controls the various operating modes of the hybrid vehicle. Operating modes of the hybrid vehicle include an electric-only power mode, a series hybrid mode, a series hybrid dual-power mode, and a parallel hybrid tri-power mode. The control system selects one of the operating modes for the hybrid vehicle based on one or more inputs and comparisons. Examples of inputs for the control system include a gear-mode, a present battery storage capacity, a present velocity of the hybrid vehicle, and the previous operating mode of the hybrid power system. The control system may also take into account whether a user has selected the electric-only power mode. The control system may also control the operations of one or more components of the hybrid vehicle while operating in one of the operating modes.

CROSS-REFERENCE TO RELATED APPLICATIONS

1) Chinese Patent Application No. 2008-10185948.3 filed on Dec. 13,2008, entitled “hybrid power driving system, controlling method thereofand vehicle comprising the same,”

2) Chinese Patent Application No. 2008-10185949.8 filed on Dec. 13,2008, entitled “hybrid vehicle comprising a torsion coupling assembly,”

3) Chinese Patent Application No. 2008-10185950.0 filed on Dec. 13,2008, entitled “hybrid driving system and vehicle comprising the same,”

4) Chinese Patent Application No. 2008-10185951.5 filed on Dec. 13,2008, entitled “hybrid power vehicle,”

5) Chinese Patent Application No. 2008-10185952.X filed on Dec. 13,2008, entitled “hybrid driving system and controlling method thereof,”

6) Chinese Patent Application No. 2008-10217019.6 filed on Oct. 11,2008, entitled “A Hybrid Power Driving System and its Control Method,”

7) Chinese Patent Application No. 2008-10217015.8 filed on Oct. 11,2008, entitled “A Hybrid Power Driving System and its Control Method,”

8) Chinese Patent Application No. 2008-10216727.8 filed on Oct. 11,2008, entitled “A Hybrid Power Driving System,”

9) Chinese Patent Application No. 2008-10217016.2 filed on Oct. 11,2008, entitled “Power Synthesis and Distribution Device and the HybridPower Driving System Using It,”

10) Chinese Patent Application No. 2008-10126507.6 filed on Jun. 24,2008, entitled “A Hybrid Driving System,”

11) Chinese Patent Application No. 2008-10126506.1 filed on Jun. 24,2008, entitled “A Hybrid Driving System and Its Driving Method,” and

12) Chinese Patent Application No. 2007-10302297.7 filed on Dec. 27,2007, entitled “The Power Control System and Method of Hybrid Vehiclewith Double Motor.”

The above enumerated patent applications are incorporated by referenceherein in their entirety.

BACKGROUND

1. Technical Field

This application relates to a hybrid power system for a hybrid motorvehicle, and in particular, to a hybrid power system that supportsmultiple operating modes and power capability for operating the drivingwheels of the motor vehicle.

2. Related Art

Motor vehicles typically operate using an internal combustible engine toconvert the energy in a combustible fluid, such as gasoline or dieselfuel, into mechanical energy to operate the driving wheels of a motorvehicle. Such fuels are expensive and contribute to environmentalpollution. As motor vehicle operators become more cost-conscious andenvironmentally conscious, an alternative to using petroleum-based fuelsis desirable. One alternative is to provide power to the driving wheelsof a motor vehicle using only electric power. However, motor vehiclesthat operate using only electric power have a short driving distance anddo not address the needs of motor vehicle operators that often drivelonger distances.

SUMMARY

A hybrid power system includes a traction motor and a motor-generator.The motor-generator and the traction motor may be selectively coupled toa battery pack. The motor-generator may receive electricity from thebattery pack and may also charge the battery pack. An internalcombustible engine further communicates with the motor-generator to forman electrical generating subsystem. The traction motor may receiveelectricity from the battery pack and may also charge the battery pack.The traction motor drives a set of driving wheels of the motor vehiclethrough a differential gear assembly.

The hybrid power system may also include other system components, suchas a vehicle controller, and a clutch or torsion distribution assembly.The clutch may selectively couple the internal combustible engine withthe traction motor to charge the battery pack, operate the drivingwheels, or both. The vehicle controller may change the operating mode ofthe hybrid power system depending on a variety of input signals. Thetorsion distribution assembly may also dampen any shock transmittedbetween the internal combustible engine and the motor-generator.

The hybrid power system may also operate according to a variety ofoperating modes, such as an electric-only operating mode, a seriesoperating mode, a series dual-power operating mode, parallel dual-poweroperating mode, and a parallel tri-power operating mode. Theelectric-only operating mode may be controlled by the driver of themotor vehicle. The series operating modes and the parallel operatingmode may be controlled by the vehicle controller. The operating modesmay also operate according to sub-modes. In one embodiment, the seriesoperating mode operates according to a series dual-power mode. Inanother embodiment, the parallel operating mode operates according to aparallel tri-power mode. Other sub-modes are also possible.

A control system controls various operating modes of a hybrid vehicle.The vehicle includes an internal combustion engine, a first electricmotor-generator, an electric traction motor, and battery pack, thecontrol system, which includes a vehicle controller. The vehiclecontroller is operative to receive a gear mode indicator, anelectric-only power mode indicator, and a present battery storagecapacity. The vehicle controller may compare the present battery storagecapacity with a battery threshold, and select an operating mode based onthe gear-mode indicator, the electric-only power mode indicator, and aresult of the comparison. The vehicle controller may output a selectedoperating mode to control the engine, the first electricmotor-generator, and the electric traction motor, so that the vehicleoperates according to the selected mode.

The vehicle controller selects an electric-only power mode as anoperating mode when the gear-mode indicator indicates either a neutral,a drive, or a reverse gear-mode, and the electric-only power modeindicator indicates that the electric-only power mode has been selected,and the present battery storage capacity is greater than theelectric-only minimum battery threshold.

The vehicle controller further compares the present battery storagecapacity with the minimum electric starting capacity threshold.determines a previous operating mode of the vehicle, and selects anoperating mode based on the comparison between the present batterystorage capacity and the minimum electric starting capacity threshold,and the determined previous operating mode.

The vehicle controller may further compare the present battery storagecapacity with an efficient operating battery threshold and select theseries mode as the operating mode when: a) the gear-mode indicatorindicates a drive or a reverse gear-mode, b) the electric-only powermode indicator indicates that the electric-only power mode is notselected, c) the present battery storage capacity is not greater thanthe efficient operating battery threshold, and d) the present batterystorage capacity is less than the minimum electric starting capacitythreshold.

The vehicle controller may receive a velocity input signal thatindicates a velocity of the hybrid vehicle and compare a value of thevelocity input signal with an upper velocity threshold. The vehiclecontroller may then select the operating mode of the vehicle based onthe comparison of the value of the velocity input signal with the uppervelocity threshold.

The battery threshold may be an efficient operating battery threshold,and the vehicle controller may select a parallel tri-power mode as theoperating mode when a) the gear-mode of the hybrid vehicle is a drive orreverse gear-mode, b) the electric-only power mode selection indicatesthat the electric-only power mode has not been selected, c) the presentbattery storage capacity is not greater than the efficient operatingbattery threshold, and d) the value of the velocity input signal isgreater than the upper velocity threshold.

The vehicle controller may select one of multiple operating mode. Forexample, an electric-only power mode defined by operating the tractionmotor to provide torque to a set of driving wheels using power suppliedsolely by the battery pack in communication with the traction motor. Aseries mode defined by operating the traction motor to provide torque tothe set of driving wheels using power supplied by the motor-generator incommunication traction motor, where excess power generated by themotor-generator is provided to charge the battery pack. A seriesdual-power mode defined by operating the traction motor to providetorque to the set of driving wheels using power supplied by themotor-generator and power supplied by the battery pack.

A parallel dual-power mode defined by operating the traction motor toprovide torque to the set of driving wheels using power supplied by thebattery pack, and by operating the internal combustion engine to provideadditional torque, where excess power generated by the motor-generatoris provided to charge the battery pack. A parallel tri-power modedefined by operating the traction motor and the motor-generator toprovide torque to the set of driving wheels using power supplied by thebattery pack, and by operating the internal combustion engine to provideadditional torque;

A method for controlling operating modes of a hybrid vehicle may includereceiving a gear mode indicator, an electric-only power mode indicator,and a present battery storage capacity, and comparing the presentbattery storage capacity with a battery threshold. The vehiclecontroller may select an operating mode based on the gear-modeindicator, the electric-only power mode indicator, and a result of thecomparison so as to control the engine, the first electricmotor-generator, and the electric traction motor, so that the vehicleoperates according to the selected mode

The vehicle controller may compare various input parameters with batterythreshold values to select the operating mode. Examples of thresholdvalues include an electric-only minimum battery threshold, a minimumelectric starting capacity threshold, an efficient operating batterythreshold, an upper velocity threshold, and a lower velocity threshold.

Other systems, methods, features and advantages will be, or will become,apparent to one with skill in the art upon examination of the followingfigures and detailed description. All such additional systems, methods,features and advantages are included within this description, are withinthe scope of the invention, and are protected by the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The system may be better understood with reference to the followingdrawings and description. The elements in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the system. In the figures, like-referenced numeralsdesignate corresponding parts throughout the different views.

FIG. 1 shows an engine/motor compartment of a motor vehicle with ahybrid power system.

FIG. 2 is a schematic system diagram for a hybrid vehicle.

FIG. 3 shows an example of the system of FIG. 2 operating in anelectric-only (EV) power mode.

FIG. 4 shows an example of the system of FIG. 2 operating in aregenerative braking mode.

FIG. 5 shows an example of the system of FIG. 2 operating in an electricstarter motor mode.

FIG. 6 shows an example of the system of FIG. 2 operating in a seriespower mode where excess generated electricity charges the battery.

FIG. 7 shows an example of the system of FIG. 2 operating in a seriesdual-power mode where all generated and stored electricity is directedto the traction motor.

FIG. 8 shows an example of the system of FIG. 2 operating in a chargingpower mode.

FIG. 9 shows an example of the system of FIG. 2 operating in aregenerative braking charging mode.

FIG. 9A shows an example of the system of FIG. 2 operating in a paralleldual-power mode where the engine and the traction motor provide torquefor the wheels.

FIG. 10 shows an example of the system of FIG. 2 operating in a paralleltri-power mode where the engine and both motors provide torque for thewheels.

FIG. 11 is a pictorial perspective view of a power plant for a hybridelectric vehicle.

FIG. 12 is an exploded view of a portion of a power assembly of thepower plant of FIG. 11, including the transmission.

FIG. 13 is a perspective view of the rank selector assembly.

FIG. 14 is a pictorial perspective view of a front cover of the powerassembly of FIG. 12.

FIG. 15 is a pictorial perspective view of a front cover of the powerassembly of FIG. 12 taken from the opposite direction as seen in FIG.14.

FIG. 16 is a pictorial perspective view of a back cover of the powerassembly of FIG. 12.

FIG. 17 is a pictorial perspective view of a back cover of the powerassembly of FIG. 12 taken from an opposite direction as seen in FIG. 16.

FIG. 18 is a side sectional view showing the clutch assembly andtransmission.

FIG. 18A is a side sectional view showing details of the clutchassembly.

FIG. 19 is an exploded view of the components of the clutch assembly.

FIG. 20 is an illustration of a clutch release bearing and cover.

FIG. 21 is a perspective view of the motor-generator housing.

FIG. 22 shows an interconnecting plate assembly of FIG. 19.

FIG. 23 is a side sectional view showing the power assembly and themotor-generator.

FIG. 24 is an illustration of a clutch release bearing.

FIG. 25 illustrates a deceleration gear of the gear reduction assembly.

FIG. 26 illustrates a main shaft of a deceleration gear.

FIG. 27 illustrates a deceleration gear.

FIG. 28 is a schematic diagram of the hydraulic system.

FIG. 29 is an illustration of the engine showing the flywheel and clutchcomponents.

FIG. 30 is a pictorial perspective view of the power plant.

FIG. 31 is a pictorial left-side elevational view of the power plant ofFIG. 30.

FIG. 32 is a back side elevational view of the power plant of FIG. 30.

FIG. 33 is a top pictorial view of the power plant of FIG. 30.

FIG. 34 is a bottom pictorial view of the power plant of FIG. 30.

FIG. 35 is a pictorial view of the power plant of FIG. 30.

FIG. 36 is a flowchart showing control flow for various operating modes.

FIG. 37 shows four graphs directed to engine and battery parameters.

FIG. 38 is a graph showing the relationship between torque output andspeed.

FIG. 39 is a pictorial perspective view showing coupling of the wheelsto the transmission.

FIG. 40 is a flowchart showing electric-only power mode operation.

FIG. 41 is a flowchart showing series mode operation.

FIG. 42 is a flowchart showing parallel mode operation.

FIG. 43 is a flowchart showing mode switching.

FIG. 44 is an electrical schematic diagram showing electrical powercomponents.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the front engine compartment 100 of a motor vehicleequipped with a multi-mode hybrid power system 102. The hybrid powersystem 102 includes an internal combustible engine 104, an electricmotor-generator 106, an electric traction motor 108, and a battery pack110. The battery pack 110 may be located within a floorboard compartmentand may not be visible in the view of FIG. 1. The hybrid power system102 may also include other components, such as, a power inverterassembly 140, radiator 146, intake manifold 160, control systemenclosure 170, shock absorber towers 180, and other components, such as,various filters, fuel injection system, master cylinder assembly, waterpump, electronic ignition housing, etc.

FIG. 2 shows a block diagram of the multi-mode or hybrid power system102, which includes a vehicle controller 202, a clutch controller 204, aclutch assembly or torque distribution assembly 206, a first inverter208, a driving inverter 210, the engine 104, the electricmotor-generator 106, the electric traction motor 108, and a connectionto a set of driving wheels 212 though a differential gear assembly 220or other similar torque transfer/gear balancing arrangement. Thedifferential gear assembly 220 permits rotation of opposing wheels, suchas the left front wheel and the right front wheel, at differentrotational speeds to facilitate turning and cornering without tireslippage or grabbing. The first inverter 208 and the driving inverter210 may be part of the vehicle controller 202 or may be separatetherefrom.

The internal-combustion engine 104 may be a gasoline engine, a dieselengine, or may use alternative fuel sources, such as methanol, ethanol,propane, hydrogen, etc. The engine 104 is preferably a four cylinderengine, but other known configurations may be used. The motor-generator106 and the traction motor 108 are preferably AC motors. However, otherelectric motors may be used, such as, switched reluctance motors, DCpermanent magnet motors, repulsion-induction motors, or other suitableelectric motors. According to established electromagnetic inductionprinciples, the motor-generator 106 and the traction motor 108 canfunction in both an electrical generator mode and in a motor mode. Whenworking in the generator mode, the respective motors convert mechanicalenergy into electrical energy, which may be used to charge the batteryin some specific embodiments. When working in the motor mode, theelectric motors convert electrical energy into mechanical energy toprovide torque indirectly or directly to the wheels of the vehicle.

In one embodiment, the vehicle controller 202 communicates with thefirst inverter 208, the driving inverter 210, and the clutch controller204. The clutch controller 204 controls the clutch 206, also referred tointerchangeably as the torque distribution system. The vehiclecontroller 202 (or controller) may be or may include one or moremicroprocessors or computers/computer systems, discrete components, etc.The vehicle controller 202 controls the operating mode of the hybridpower system 102. The operating mode of the motor vehicle may determinethe specific operating function of one or more components of the hybridpower system 102 including, but not limited to, the internal-combustibleengine 104, the motor-generator 106, the electric traction motor 108,the clutch controller 204, the torque distribution assembly 206, thefirst inverter 208, and the driving inverter 210.

The engine 104 communicates with the electric motor-generator 106 toreceive rotational power from the electric motor-generator 106 when thevehicle controller 202 first starts the engine 104. Thus, themotor-generator 106 can operate as a conventional starter motor. Theengine 104 is also operative to provide torque to the electricmotor-generator 106 for charging the battery pack 110 or for providingpower to the traction motor 108 in a specific operating mode.

The electric traction motor 108 is configured to provide torque to thedriving wheels 212 through a gear reduction assembly and thedifferential gear assembly 220. The gear reduction assembly and thedifferential gear assembly 220 may be combined into a single assembly.When the clutch 206 is engaged, the electric traction motor 108 mayreceive additional torque from the engine 104, in addition to receivingelectrical power from either the battery or from the motor-generator106, depending on the mode and the load conditions. In addition, theelectric traction motor 108 may charge the battery pack 110 throughregenerative braking or other mechanism to charge to the battery pack110.

The battery pack 110 provides electrical power at about 330 volts DC tothe first inverter 208, which converts the DC power to AC power. Thefirst inverter 208 provides the AC power to the motor-generator 106, andmay be controlled by the controller 202 to provide about 0 volts AC (offstate) to about 330 volts AC (full power state) to the motor-generator106. Similarly, the battery pack 110 provides electric power at about330 volts DC to the driving inverter 210, which converts the DC power toAC power. The driving inverter 210 provides AC the power to the tractionmotor 108, and may be controlled by the controller 202 to provide about0 volts AC (off state) to about 330 volts AC (full power state) to thetraction motor 108. Preferably, the motor-generator 106 and the tractionmotor 108 operates in an AC multi-phase configuration.

The battery pack 110 is not limited to a specific voltage, and based onits configuration and arrangement of cells, may provided a different DCvoltage, with the specific motor-generator 106 and traction motor 108selected for efficient operation in the voltage range provided by thebattery pack 110. Although the first inverter 208 and the drivinginverter 210 are shown separately in the figures, these components maybe contained in a single package, chip, or component, or may beconfigured as multiple and separate components, which may be included inor may be separate from the controller 202. The battery pack 110 mayalso provide electrical power to the engine 104 for electronic ignitionand spark generation, vehicle controller 202 operation, clutchcontroller 204 operation, vehicle lighting and accessory operation, andany other component of the vehicle.

Regarding the terminology for the modes and sub-modes as used in thisdocument, a vehicle that uses only electric motors without any form ofinternal-combustion engine is referred to as an electric vehicle or pureelectric vehicle (EV). A vehicle that uses both an internal-combustionengine and one or more electric motors is loosely referred to as ahybrid vehicle or operates in a hybrid mode. Hybrid operation mayinclude series hybrid mode and parallel hybrid mode.

A series hybrid mode means that the internal-combustion engine providestorque only to the motor-generator to generate electricity, and that notorque from the internal-combustion engine is directly fed to the drivewheels. Multiple sub-modes within the series hybrid mode may beprovided, such as series mode and series dual-power mode, depending uponwhich components and how many components are engaged to power thevehicle.

A parallel hybrid mode means that the internal-combustion engineprovides torque to the motor-generator to generate electricity, and alsoprovides torque to drive the wheels, typically through an arrangement ofa clutch or other engagable mechanical arrangement. Again, multiplesub-modes within the parallel hybrid mode may be described, such asparallel dual-power mode and parallel tri-power mode, depending uponwhich components and how many components are engaged to power thevehicle. The various operating modes are explained in further detailwith reference to FIG. 3 through FIG. 10.

A user-selectable switch (“EV/HEV control input”) on the dashboard ofthe vehicle may permit the operator to switch between a pure electricdriving mode (EV—electric vehicle mode) or a hybrid driving mode (HEV).The switch may be a depressible button, knob, lever, or other controlinput, and may be located in the interior of the motor vehicle or inanother location of the motor vehicle. The controller 202 utilizes thestate of the switch as an input operating signal to determine whetherthe motor vehicle operator has selected an electric-only mode or ahybrid mode.

FIG. 3 shows an example of the hybrid power system 102 operatingaccording to an electric-only power mode (EV mode). In oneimplementation of the electric-only power mode, the battery pack 110provides power to the traction motor 108 via the driving inverter 210.The clutch 206 is not engaged such that the motor-generator 106 and thetraction motor 108 are not coupled. The engine 104 is not powered (thusshown in dashed lines) and the traction motor 108 provides all power tooperate the driving wheels 212. The hybrid power system 102 may operatein the electric-only mode when a motor vehicle operator selects theelectric-only mode using the EV/HEV input control. For example, when theEV/HEV input control is manipulated to select the electric-only mode,the vehicle controller 202 may communicate one or more output controlsignals to instruct the clutch controller 204, the electricmotor-generator 106, and the electric traction motor 108 so that onlythe electric traction motor 108 operates the driving wheels 212. Otheroutput control signals may be provided. Components shown in dashed linesin FIGS. 3-10 indicate that these components may be inactivate in thisspecific mode.

FIG. 4 shows an example of the hybrid power system 102 operatingaccording to a regenerative braking mode. In the regenerative brakingmode, the traction motor 108 accepts torque from the driving wheels 212and converts the torque into AC Power. The traction motor 108 then feedsthe AC power to the driving inverter 210, and then to the battery pack110 to charge the battery pack 110. In one implementation, the hybridpower system 102 operates in regenerative braking mode while the motorvehicle is decelerating, such as when the driver does not depress orminimally depresses the accelerator pedal, which may also be dependentupon the road gradient.

Although the motor-generator 106 may charge the battery 110 and/orprovide electricity to the traction motor 108 under engine powerdepending on the operating mode, the motor-generator 106 preferably doesnot charge the battery 110 during a regenerative breaking mode whencoupled to the driving wheels through the engaged or closed clutch 206in a hybrid parallel mode described below.

One or more input operating signals may cause the vehicle controller 202to operate in the regenerative braking mode. For example, the hybridpower system 102 may operate in the regenerative braking mode when anaccelerator depth input operating signal is below a predeterminedthreshold value, such as when the driver is not depressing theaccelerator pedal or is minimally depressing the pedal. Regenerativebraking mode may also be operative when a brake input operating signalis above a predetermined threshold value, which indicates that thedriver is depressing the brake pedal. In one implementation, the hybridpower system 102 operates in the regenerative braking mode when theaccelerator depth input operating signal is 0 (meaning no pedaldepression) and the brake input operating signal is greater than 0(indicating some depression of the brake pedal).

FIG. 5 shows the hybrid power system 102 operating according to anelectric starting mode. In the electric starting mode, the battery pack110 supplies power to the electric motor-generator 106 to start theengine 104. The motor-generator 106 may provide torque to the engine 104until the engine 104 starts and/or obtains a desired rotational speed.In one implementation, the motor-generator 106 rotates the engineflywheel until the engine is rotating at about 1200 RPM. Once thisoccurs, the engine 104 is started via an electronic ignition system (notshown), which provides the proper spark to the cylinders using theappropriate timing scheme.

Depending upon operating conditions and whether the system is operatingin a series power mode or a parallel power mode, the vehicle controller202 may change the engine speed. When operating in a series mode, thevehicle controller 202 may set the engine speed to the most efficientoperating RPM in which to rotate the motor-generator 106 to generateelectricity. When operating in a parallel mode where the engine 104 iscoupled to the wheels 212 through the clutch 206, the vehicle controller202 may set the engine speed based upon system parameters, such as forexample, the speed of the vehicle, the acceleration demand, the load onthe vehicle (hill climbing), and other parameters.

FIG. 6 shows the hybrid power system 102 operating according to a serieshybrid power mode where excess generated electricity is used to chargethe battery 110. In series hybrid power mode, the engine 104 drives themotor-generator 106 to generate electricity to charge the battery pack110 through the first inverter. In addition, the traction motor 108 mayreceive power from the motor-generator 106 to operate the driving wheels212 via the driving inverter 210. For example, where the motor-generator106 generates power greater than the amount of power consumed by thetraction motor 108, the traction motor 108 may accept the powergenerated by the motor-generator 106, and the excess power may bediverted to charge the battery pack 110.

FIG. 7 shows the hybrid power system 102 operating according to a serieshybrid dual-power mode. When the traction motor 108 requires all of thepower or more power than is generated by the motor-generator 106, thetraction motor 108 may receive additional power from the battery pack110. Hence, in series hybrid dual-power mode, the traction motor 108operates the driving wheels 212 while the motor-generator 106 and thebattery pack 110 provide power to the traction motor 108.

FIG. 8 shows an example of the hybrid power system 102 operatingaccording to an idle-charging mode. In idle-charging mode, the engine104 drives the motor-generator 106, which charges the battery pack 110.In one implementation, the hybrid power system 102 operates according tothe idle-charging mode when the gear-mode input operating signalindicates that the motor vehicle is in a “park” or “neutral” gear-mode.However, the hybrid power system 102 may operate according to thecharging mode based on other combinations of input signals.

FIG. 9 shows the hybrid power system 102 operating according to aregenerative braking and charging mode. In the regenerative braking andcharging mode, one or more components charge the battery pack 110 usingone or more charging mechanisms. For example, through regenerativebraking, the traction motor 108 operates as a generator by acceptingtorque from the driving wheels 212 to provide electricity to the batterypack 110. Simultaneously, the engine may drive the motor-generator 106to further charge the battery pack 110. The hybrid power system 102 mayoperate in the regenerative charging mode when one or more inputoperating signals exceed or fall below a predetermined threshold value.For example, the hybrid power system 102 may operate in the regenerativecharging mode when the accelerator depth input operating signal is 0 andthe brake input operating signal is above 0.

FIG. 9A shows an example of the hybrid power system 102 operatingaccording to a parallel hybrid dual-power mode. In this mode, the clutchor torque distribution assembly 206 is engaged. With the clutch 206engaged, the engine 104, through the direct coupling with themotor-generator 106 and the traction motor 108, provides torque tooperate the driving wheels 212. Thus, the engine and the traction motor(under battery power) provide torque to the driving wheels 212. Further,in this mode, the motor-generator 106, turning under power from theengine 104, may provide electricity to charge the battery pack 110. Inan alternate embodiment of the parallel hybrid dual-power mode, themotor-generator 106 need not necessarily provide any charging power tothe battery pack 110.

FIG. 10 shows an example of the hybrid power system 102 operatingaccording to a parallel hybrid tri-power mode. In this mode, the clutchor torque distribution assembly 206 is engaged. With the clutch 206engaged, the engine 104, through the direct coupling with themotor-generator 106 and the traction motor 108, provides torque tooperate the driving wheels 212. Thus, the engine and both motors providetorque to the driving wheels 212. In addition, the battery pack 110provides power to the motor-generator 106 and to the traction motor 108to further increase the amount of torque directed to the driving wheels212.

Note that the configuration and coupling of the clutch 206 and thetraction motor 108 may vary in some embodiments. In one embodiment shownin FIG. 11, the output of the clutch or torque distribution assembly206, rather than being coupled directly to the traction motor 108, maybe alternatively coupled to a deceleration mechanism or reduction gear,which may be housed in the transmission gear reduction assembly (alsoreferred to as the transmission) 1108. The transmission gear reductionassembly 1108 may include one or more gears or gear assemblies (forexample, a primary and a secondary deceleration gear) that physicallycouple the high-speed rotational output of the traction motor 108 withthe lower speed input portion of the differential gear assembly 220 orother gear mechanism. As mentioned above, in some embodiments, thedeceleration mechanism or reduction gear may be combined with thedifferential gear assembly 220.

In another embodiment for example, the deceleration mechanism orreduction gears may include helical gears, planetary gears, straightgears, and combinations of these and other gears. Accordingly, thetransmission gear reduction assembly 1108 may include an input couplingor gear input configured to receive torque from the output of thetraction motor 108. In an alternate embodiment, the transmission gearreduction assembly 1108 may include a second input or port configured toreceive rotational torque from another source of power.

Referring now to specific parameters of the engine 104 and motors 106and 108, in one specific embodiment, the engine 104 may have adisplacement of about 998 cc, a maximum output torque of about 90Newton-meters, a maximum output power of about 50 kW, and a maximumoutput speed of about 6000 RPM. In another embodiment themotor-generator 106 may have a maximum output torque of about 150Newton-meters, a maximum output power of about 20 kW, and a maximumoutput speed of about 5000 RPM. In a further embodiment the tractionmotor 108 may have a maximum output torque of about 400 Newton-meters, amaximum output power of about 50 kW, and a maximum output speed of about6000 RPM.

Although the battery 110 is described and shown in the above figures asreceiving power from the motor-generator 106 and/or the traction motor108 when those components operate as electrical generators, the batterymay also be charged from an external electrical source. Accordingly, thehybrid system is also referred to as a “plug-in” hybrid system. As shownin FIG. 2, the battery may be coupled to an external charging interface230, which includes an inverter 234. For example, the charging interface230 may accept and direct power received from the electrical “grid” 240through a plug 242 and socket 244 arrangement. In one embodiment, theinput power may be standard 120-240 VAC power from a standardreceptacle, also referred to as “wall power” or household power. Asuitable DC voltage source, such as a large storage battery at acharging facility may also charge the battery. Appropriate charging ofthe battery 110 through plug-in charging permits the vehicle to operatein the EV mode without using the engine 104 at all.

The battery pack 110 preferably uses lithium polymer and/orlithium-ion-phosphate technology that permits the vehicle to travelabout at least 50 km on a single battery charge. In a preferablyembodiment, the vehicle may have an operative travel range of about atleast 100 km on a single battery charge when operating in pure EV mode.

In one embodiment, the vehicle includes about 50 lithium battery cellsare coupled in series. In a preferred embodiment, about 100 individuallithium battery cells are coupled in series, where each battery cell hasa voltage of about 3.3 volts. Thus, the total voltage output of thebattery cells is about 330 volts, which is a suitable working voltagefor the motor/generator 106 and the traction motor 108. Other workingvoltages may be used depending on the selected electric motors and thenumber of series-coupled batteries. In other embodiments, the batterypack 110 may include other types of batteries, such as lead-acidbatteries, nickel-chromium batteries, nickel-hydride batteries.

Returning back to FIG. 11, this figure illustrates one embodiment of apower plant 1104, which may include the engine 104, the motor-generator106, and the traction motor 108. Also shown is the gear reductionassembly (also referred to as the transmission) 1108, which includes oneor more gear assemblies that physically couple the high-speed rotationaloutput of the traction motor 108 with the lower speed input portion ofthe differential gear assembly 220 via a primary and a secondarydeceleration gear arrangement. The gear reduction assembly 1108 furtherincludes a rank unit 1250 (FIG. 12), which provides the mechanicalgearing to facilitate selection of a gear mode, such as park, neutral,reverse, and drive. The engine 104 may include standard components, suchas an oil pan 1112, oil filter 1114, air filter housing 1116, and thelike.

FIG. 12 shows an exploded view of some of the components enclosed withinthe transmission or gear reduction assembly 1108, which is coupledbetween the motor-generator 106 and the traction motor 108. Themotor-generator 106 and the traction motor 108 are shown generally inFIG. 12. On one side of the gear reduction assembly 1108, a tractionmotor housing 1222 houses the traction motor 108, and includes atraction motor housing cover 1224, which together define a tractionmotor assembly 1226. The traction motor 108 includes a rotor 1230 and astator 1232. On an opposite side of the gear reduction assembly 1108, amotor-generator housing 1240 houses the motor-generator 106, andincludes a motor-generator housing cover 1242, which together define amotor-generator assembly 1244. The motor-generator 106 similarlyincludes a rotor 1246 and a stator 1248.

The rank unit 1250 is located within the transmission or gear reductionassembly 1108, which is between the traction motor assembly 1226 and themotor-generator assembly 1244, and is also referred to as the gearselector. The rank unit 1250 or selector is typically manually operatedby the driver to select the gear mode, such as park, neutral, drive, andreverse. The controller 202 may recognize the position or operating modeof the rank unit 1250 via a gear-mode sensor or other sensor incommunication with the vehicle controller 202. FIG. 13 shows the rankunit 1250 in greater detail.

Referring to FIGS. 11-13, the gear reduction assembly 1108 or“transmission” includes the rank unit 1250. As described above, the gearreduction assembly 1108 physically couples the high-speed rotationaloutput of the traction motor 108 with the lower speed input portion ofthe differential gear assembly 220. A half-shaft (see FIG. 39) couplesthe output of the differential gear assembly 220 through an opening oroutput port 1130 in the gear reduction assembly 1108 to each of thedriving wheels 212. In a preferred embodiment, the gear reductionassembly 1108 houses the differential gear assembly 220, which in turn,provides an output to each of the two front wheels 212.

FIG. 14 illustrates one embodiment of the motor-generator housing 1240showing an external perspective, while FIG. 15 shows the motor-generatorhousing from an internal perspective. Similarly, FIG. 16 illustrates oneembodiment of the traction motor housing 1222 showing an externalperspective, while FIG. 17 shows the traction motor housing from aninternal perspective.

FIG. 18 shows a torque distribution assembly 1802, also referred tointerchangeably as the clutch 206 in FIGS. 2 through 10, which isoperatively coupled to an engine flywheel 1804. The flywheel 1804receives rotational power from a crankshaft 1805 of the engine 104. Thetorque distribution assembly 1802 is responsible for distributing thetorque generated by the engine 104 and the motors 106, 108 according totwo different mechanical modes.

In a first mechanical mode, the torque distribution assembly 1802 mayprovide a true “clutch function” to selectively engage and disengage theengine 104 from the traction motor 108. In a second mechanical mode, thetorque distribution assembly 1802 provides a “soft” coupling ortorsional connection between the engine 104 and the motor-generator 106.The soft or torsional connection dampens or reduces the shock or impactcaused by abrupt rotational changes when the engine 104 initiallystarts, and conversely, provides damping or shock reduction when themotor-generator initially provides power under battery operation. Suchrotational shock or rotational difference and/or misalignment less thana predetermined amount may be absorbed or smoothed by the torquedistribution assembly 1802.

Note that the coupling between the motor-generator 106 and the engine104 is always “connected” and cannot be selectively disengaged. Rather,there is a loose or shock-absorbing connection between the engineflywheel 1804 and the motor-generator 106, but they are nonethelessconnected, and disengagement is not possible in specific embodiments.Because the motor-generator 106 and the engine 104 are connected, thedifference in rotational speed, or angular alignment between the engineand the motor-generator 106 may only occur for a small fraction of arevolution, for example for a small sector of a revolution, such asabout less than about 3 to about 10 degrees.

As shown in FIGS. 18, 18A, and in the exploded view of FIG. 19, in oneembodiment, the torque distribution assembly 1802 is coupled to theflywheel 1804 with connectors or bolts 1805. The torque distributionassembly 1802 includes a driven plate assembly 1806, a cover assembly1808, an interconnecting plate assembly 1810, a release bearing assembly1812, a hollow drive shaft 1814 configured to rotate the rotor 1246 ofmotor-generator 106, and a transmission spindle 1816 configured torotate the rotor 1230 of the traction motor 108 through a rotor shaft1820. The transmission spindle 1816 is received through a toothed orspline-like aperture 1904 in the driven plate assembly 1806. Thus, thetransmission spindle 1816 rotates when the driven plate assemblyrotates, which occurs when the driven plate assembly is engaged againstthe rotating flywheel 1804.

The selectively engagable clutch coupling connected between the flywheel1804 and the traction motor 108, referred to as the first mechanicalmode, will now be described. Selective engagement of the clutch functionis controlled by the vehicle controller 202 via the clutch controller204, which controls activation of the release bearing assembly 1812. Therelease bearing assembly 1812 is located within the hollow drive shaft1814 of the motor-generator 106, and may be spring-loaded to performselective engagement and disengagement. Note that in a preferableembodiment, the release bearing 1812 is hydraulically actuated. However,any suitable engagement system may be used to activate and deactivatethe release bearing assembly 1812. For example, the release bearingassembly 1812 may be electrically activated by a solenoid or othermagnetic switch, or may be pneumatically controlled using a supply ofcompressed air or gas. In the preferably embodiment, for example, theclutch controller 204 may activate hydraulic power via a hydraulicpiston 1826 to cause the release bearing assembly 1812 to engage anddisengage.

The driven plate assembly 1806 may include a rim or ring of frictionalmaterial or a friction plate 1906, which may be formed of asbestos orsynthetic frictional material for example. When the driven plateassembly 1806 is pushed against the flywheel 1804 during clutchengagement, the friction plate 1906 contacts the surface of the flywheel1804 creating static friction during slippage as the driven plateassembly 1806 begins to rotate. After several revolutions of theflywheel 1804, the slippage is eliminated, and the driven plate assembly1806 rotates along with the flywheel 1804 under full engagement. Therotating driven plate assembly 1806 causes the transmission spindle 1816to rotate in unison with the rotor 1230 of the traction motor 108.

The driven plate assembly 1806 is housed within the cover assembly 1808.The cover assembly 1808 includes a diaphragm spring 1910 or otherflexible spring-like member. The diaphragm spring 1910 flexes inresponse to reciprocating movement of the piston 1826 of release bearingassembly 1812, which may be received through an opening 1914 in thecover assembly 1808. Another opening 1916 in the interconnecting plateassembly 1810 permits the piston 1826 of the release bearing assembly1812 to contact the diaphragm spring 1910.

When the clutch is engaged, as shown when the release bearing assembly1812 is in the position indicated by arrow “A” 1922, the piston 1826 isout of contact with the diaphragm spring 1910. Thus, the diaphragmspring 1910 is in a non-flexed orientation, and presses the frictionplate 1906 of the driven plate assembly 1806 against the surface of theflywheel 1804. This engaged position is also shown in FIG. 18, and isdescribed in greater detail with respect to FIG. 18A.

Conversely, when the clutch is disengaged, as shown when the piston 1826is in the position indicated by arrow “B” 1926, the piston pressesagainst the diaphragm spring 1910, which causes it to be in a flexedorientation. The un-flexing of the diaphragm spring 1910 pulls thedriven plate assembly 1806 away from the flywheel 1804, thus disengagingthe driven plate assembly 1806 from the rotating flywheel 1804, and isalso described in greater detail with respect to FIG. 18A. Note that indifferent embodiments, the orientation of the diaphragm spring 1910 mayeither be in a flexed orientation or in an un-flexed orientation whenthe clutch is engaged or disengaged, depending upon the preferred“flex-state” of the diaphragm spring 1910. This may be determined by theamount of time or how often the clutch generally remains engaged duringnormal driving. Preferably, during normal driving where the clutch doesnot couple the engine 104 to the wheels (most of the time), theorientation of the diaphragm spring 1910 and the clutch assembly isconfigured so that minimum wear between components occurs.

FIG. 18A shows the interaction between the release bearing assembly1812, the piston 1826, and the diaphragm spring 1910 in greater detail.The piston 1826 may move relative the release bearing assembly 1812, asshown by the arrows “A” 1922 and “B” 1926 of FIGS. 18 and 19, while therelease bearing assembly 1812 may remain in a fixed position in oneembodiment. A distal end of the piston 1826 may include a race bearing1830 or ball-bearing race, that is configured to contact the diaphragmspring 1910 as the piston 1826 moves inwardly and outwardly so as toisolate any rotational differences. A flange or pivot 1836, which may beformed in or from a portion of the cover assembly 1808, in oneembodiment, may provide a pivot point for flexing of the diaphragmspring 1910.

When the piston 1826 is activated to move in the inward direction shownby arrow “B,” a radially-inward portion 1840 of the diaphragm spring1910 moves in the same direction as the piston 1826 moves. However, dueto the pivot point provided by the flange 1836, a radially-outwardportion 1844 of the diaphragm spring 1910 moves in the oppositedirection as the piston 1826. Such movement in the opposite directioncauses the radially-outward portion 1844 of the diaphragm spring 1910 to“pull” or move the driven plate assembly 1806, along with the frictiondisk 1906, away from the surface of the flywheel 1804, effectivelydisengaging the clutch assembly.

Conversely, when the piston 1826 is activated to move in the outwarddirection shown by arrow “A, the radially-inward portion 1840 of thediaphragm spring 1910 moves in the same direction as the piston 1826.However, again due to the pivot point provided by the flange 1836, theradially-outward portion 1844 of the diaphragm spring 1910 moves in theopposite direction as the piston 1826 moves. Such movement in theopposite direction causes the radially-outward portion 1844 (and theentire diaphragm spring 1910) to “release” and return to its normalorientation, which forces the driven plate assembly 1806, along with thefriction disk 1906, into contact with the surface of the flywheel 1804,which effectively maintains clutch engagement.

The hydraulic coupling to the release bearing assembly 1812 is shown ingreater detail in FIG. 20, and is shown coupled to the motor-generatorhousing cover 1242. Again, this coupling may not necessarily behydraulic in nature depending upon the specific embodiment, and may, forexample, be an electrical coupling. FIG. 21 shows motor-generatorhousing cover 1242 with the release bearing assembly 1812 omitted, butillustrates a hydraulic line 2104 or other connection to the releasebearing assembly 1812.

Referring back to FIGS. 18, 18A, and 19, the release bearing assembly1812 includes the through-bore or cylindrical aperture 1904 configuredto receive transmission spindle 1816. As described above, the piston1826 of the release bearing assembly 1812 may be controlled to pressagainst the diaphragm spring 1910 via the race bearing 1830 to disengagethe driven plate assembly 1806, or to release the diaphragm spring 1910so that power is transferred from the flywheel 1804 to the driven plateassembly 1806 and in turn, to the transmission spindle 1816. Thisprovides directly-coupled rotational power to the traction motor 108 viathe transmission spindle 1816. In this way, additional power from theengine 104 may be selectively coupled to the rotor shaft 1820 of thetraction motor 108 in a true clutch mode to provide maximum power duringthe parallel tri-power mode.

The torque distribution assembly 1802, for example, may provide trueclutch function to couple the engine 104 output with the traction motor108 when the vehicle is climbing or accelerating. The torquedistribution assembly 1802 may also be engaged according to the requiredpower demands of the traction motor 108 and the motor-generator 106. Forexample, when the power output by the battery pack 110 is insufficient,the torque distribution assembly 1802 may couple the engine 104 to thetraction motor 108 to provide extra power.

One or more operating input signals or status input signals may affectcontrol of the torque distribution assembly 1802. For example, when theoperating input signals or the status input signals indicate that themotor vehicle is operating at a high speed or with increased powerdemands (e.g., hill climbing, passing), the torque distribution assembly1802 may cause the piston 1826 of the release bearing assembly 1812 tomove out of contact with the diaphragm spring 1910 (clutch engaged).Conversely, when the operating input signals or the status input signalsindicate that the motor vehicle is operating at a low speed or withdecreased power demands, the torque distribution assembly 1802 may causethe piston 1826 of the release bearing assembly 1812 to contact and flexthe diaphragm spring to disengage the clutch.

FIG. 18 shows that the torque distribution assembly 1802 is coupled tothe transmission 1108. The transmission 1108 houses a primarydeceleration gear 1841 configured to receive the high speed rotationaloutput of the transmission spindle 1816, and convert its output to alower rotational speed. A secondary deceleration gear 1842 coupled tothe primary deceleration gear 1841 further reduces the rotational outputspeed. Finally, a driving gear 1846 receives the output from thesecondary deceleration gear 1842 and couples the reduced output to thedifferential gear assembly 220, which in turn supplies torque to thedriving wheels 212.

Turn back to the torque distribution assembly 1802 of FIG. 18, thetorsional or “loose” coupling between the flywheel 1804 and themotor-generator 106 will now be described (“the second mechanicalmode”). FIG. 22 shows an exploded view of the interconnecting plateassembly 1810 of FIG. 18. The interconnecting plate assembly 1810 iscoupled to the cover assembly 1808, and thus rotates with the coverassembly 1808, which is bolted to the flywheel 1804. In one embodiment,the interconnecting plate assembly 1810 includes an inner sideboard 2202in communication with an inner gasket 2204, and a torsion plate 2206.The inner sideboard 2202 may be fixed to a portion of the cover assembly1808 by welds, bolts, rivets, metal formation, or other suitabletechniques to secure the interconnecting plate assembly 1810 to thecover assembly 1808.

The torsion plate 2206 may include one or more shock absorbing elementsor springs 2208. The shock absorbing elements may be made of a resilientor deformable material. Other suitable torsional, deformable, or shockabsorbing elements may be used. For example, the shock absorbingelements may be metal or composite coil springs or compression springs,blocks of compressible rubber, or other deformable material. The torsionplate 2206 also communicates with an outer gasket 2210 and an outersideboard 2212. The inner gasket 2204 and the outer gasket 2210 mayprovide further shock absorbing or damping capability, which may reducethe shock transmitted to or from the hollow shaft 1814.

The inner gasket 2204 and the outer gasket 2210 may be made of adeformable or compressible material, such a rubber, foam, or othersuitable material that is adapted to provide a cushion to dampenmechanical movement and vibration. Accordingly, the interconnectingplate assembly 1810 provides multiple features to reduce and dampenshock and vibration between the engine 104 and the motor-generator 106.

The interconnecting plate assembly 1810 using the above-describedcomponents may provide a torsional or soft coupling between the engine104 and the motor-generator 106 to reduce or absorb shock absorption.The hollow shaft 1814 is received through the aperture 1916 of theinterconnecting plate assembly 1810 and is coupled to the torsion plate2206. The torsion plate 2206 may have a splined or toothed aperture 2216configured to receive and make positive engagement with the hollow shaft1814, which may also have a spline or toothed portion. Thus, the hollowshaft 1814 rotates along with the interconnecting plate assembly 1810,the cover assembly 1808, and the flywheel 1804 when the engine 104rotates.

In particular, the springs 2208 of the torsion plate 2206 may beconfigured to absorb shock when either the engine 104 or themotor-generator 106 rapidly changes rotational speed, such as uponstarting or shutting-down. The springs 2208 of the interconnecting plateassembly 1810 permit the interconnecting plate assembly to rotationallyflex relative to the cover assembly 1808. The springs 2208 may bepartially received in a plurality of recesses 2220 in the innersideboard 2202 to permit the torsion plate 2206 to rotationally flex orslip a few degrees relative to the cover assembly 1808. This may providedamping to reduce shock and vibration that may be transmitted from thetorsion plate 2206 to the hollow shaft 1814.

Such rotationally flexing represents an angular misalignment between thetorsion plate 2206 and the clutch cover 1808 (and hence with theflywheel). The maximum amount of any such angular misalignment isgoverned by an arcuate length 2230 of the recesses 2220 in the innersideboard 2202, and in particular, an arc 2234 subtended by the recesses2220. Such angular misalignment may range from about 0 degrees to about20 degrees. Preferably, the angular misalignment typically ranges fromabout 0 degrees to about 10 degrees. The springs may compress anddecompress in either a clockwise or counter-clockwise direction, andsuch compression and decompression may represent vibration between thecomponents.

FIG. 23 shows a pictorial representation of the torque distributionassembly 1802 coupling the engine flywheel 1804 to the components of themotor-generator 106. FIG. 24 shows an enlarged view of the releasebearing assembly 1812.

Referring FIGS. 11, 12, and 25, the gear reduction assembly 1108 isdescribed in further detail. As described above, the gear reductionassembly 1108 houses the rank unit 1250 and a variety of transmissiongears. FIG. 25 shows an example of one type of deceleration or reductionmechanism, and in particular, shows a transmission gear or reductiongear 2502. However many different types and combinations of gears may beused. For example, the gear reduction assembly 1108 may include helicalgears, planetary gears, straight gears, and combinations of these gears.

FIGS. 26 and 27 show further examples of reduction or deceleration gears2702 and gear assemblies 2602 that may be included in the gear reductionassembly 1108. The deceleration gear 2702 shown in FIG. 27 includes anaccessory shaft 2704. The gear assembly 2602 may include an input shaft2604 to facilitate torque transfer to other gearing mechanisms. The gearassembly 2602 may rotate in conjunction with reduction gear 2702 toprovide rotational reduction. The gear reduction assembly 1108 includesall of the required gearing, preferably including the differential gearassembly 220, which together define the transmission. The gear reductionassembly 1108 or transmission is a single rank, two-stage drive. Asdescribed above, the gear reduction assembly 1108 or transmission mayinclude the primary decelerating gear 1841, the secondary deceleratinggear 1842, and the driving gear 1846. Preferably, the differential gearassembly 220 is physically contained within the gear reduction assembly1108, and receives rotational input from the driving gear 1846. In someembodiments, the differential gear assembly 220 may be physicallyseparate from or external to the gear reduction assembly 1108.

The gear reduction assembly 1108 preferably includes only a singletransmission gear so that the gear-shifting disadvantages associatedwith automatic transmissions and/or manual shifting are avoided. Also,no gear synchronizer or gear-shifting executive mechanism is needed,which simplifies the internal structure of the gear reduction assembly1108, reduces the weight, and conserves space in the axial direction. Inaddition to the weight reduction, the engine 104 need only be activatedin high-speed or passing mode, and thus can operate at its mostefficient operating RPM, thus increasing fuel economy. Further, thevarious operating modes facilitate engine operation at its mostefficient rotational speed so that maximum efficiency is achieved.Inefficient rotary speeds are avoided, such as idle and low rotaryspeeds. Moreover, only a very low-power, fuel efficient engine 104 isneeded, which lowers manufacture costs, reduces size, and permits lesscomplex factory assembly.

FIGS. 29-35 are further pictorial representations showing the engine104, motor-generator 106, traction motor 108, and torque distributionassembly 1802, in various views. In particular, FIG. 29 shows thetorsion plate 2206 with the exposed springs 2208 configured to andreduce shock and vibration between the engine 104 and themotor-generator 106.

FIG. 39 shows the connection of the driving wheels 212 to the outputs ofthe differential gear assembly 212, which may be housed within the gearreduction assembly or transmission 1108. In some embodiments, the gearreduction assembly 1108 may include two openings that provide access tocorresponding port. A half-shaft 3902 and universal joint 3908distributes the rotational output from the differential 220 through eachport to the corresponding driving wheel 212. Each half-shaft 3902 may becoupled to the final gear stage of the differential gear assembly 220,which is preferably located within the gear reduction assembly 1108.

As shown in the above figures, and in particular, FIG. 39, the engine104, the motor-generator 106, the traction motor 108, the gear reductionassembly 1108 (which includes the differential assembly 220) are housedwithin an engine compartment and located between and above the two frontwheels. In that regard, the motor-generator 106, the traction motor 108,the gear reduction assembly 1108, are located above a centerline of thewheels, which may be defined by the position of the half-shafts 3902.The engine 104 is substantially above the centerline of the wheels. Themechanical power coupling provided by the flywheel 1804, the torquedistribution assembly 1802, and the spindle 1816, and other componentsare arranged in a generally linear manner from the engine 104 to themotor-generator 106, and from the motor-generator to the traction motor108.

FIG. 28 is a schematic diagram of a hydraulic control system 2800configured to actuate various components in the torque distributionsystem 1802, and in particular, the release bearing assembly 1812 in theembodiments using hydraulic actuation. In one embodiment, the hydraulicflow path with respect to energy storage is as follows: Fluid flows froma hydraulic fluid reservoir 2802 through a filter 2804, to a fluid pumpassembly 2806, through a check valve 2808, into an accumulator 2810, andback into the hydraulic fluid reservoir 2802.

In another embodiment, the hydraulic flow path with respect to a toppressure diaphragm spring 2820 (may also be referred to as 1910) whenthe clutch (release bearing assembly 1812) is separated, is as follows:Fluid flows from the accumulator 2810 through a first solenoiddirectional control valve 2822, through a large damping hole 2824, andto the release bearing assembly 1812.

In a further embodiment, the hydraulic flow path with respect tohydraulic fluid return, when the clutch (release bearing assembly 1812)is engaged or connected, is a follows: Fluid flows from the releasebearing assembly 1812 through a small damping hole 2826, through asecond solenoid directional control valve 2828, and back to thehydraulic fluid reservoir 2802.

The clutch (release bearing assembly 1812) is controlled via “energystorage” using the top pressure diaphragm spring 2820 and return fluidflow. Electrical signals (2830-first pressure sending signal,2832-second pressure sending signal) generated by the various sensorsare processed by the clutch controller 204. The clutch controller 204may also process a clutch separation signal 2834 and a clutch connectedsignal 2836. The clutch controller 204 controls the hydraulic systempressure via electromagnetic valves and the hydraulic fluid pumpassembly 2806 to ensure proper operation of the release bearing assembly1812. The accumulator 2810 acts as the main source of energy while anelectrical pump motor 2840 provides mechanical power to the hydraulicfluid pump assembly.

In known hydraulic systems, if the hydraulic fluid pump constantlypressurizes the hydraulic cylinder directly, a pump having a large fluidvolume is needed (along with a large motor to pressurize the pump), andpremature failures may result due to frequent hydraulic startup andlarge hydraulic shocks. However, the hydraulic system described in thevarious embodiments is advantageous because the fluid pump assembly 2806pressurizes the accumulator 2810, where the accumulator, in turn,pressurizes the release bearing assembly 1812. This permits use of ahydraulic pump having smaller volume (along with a smaller pump motor2840), reduces pump startup time, increases the pump lifetime, andreduces hydraulic fluid shock in the system. Use of the damping holes2824 and 2826 increases the control accuracy of the hydraulic system2800. In particular, the large damping hole 2824 permits quick clutchseparation, while use of the small damping hole 2826 ensues operation ofthe clutch in the half-running-in condition.

Referring back to FIGS. 1-10, the vehicle controller 202 may accept avariety of input operating signals to facilitate changing or modifyingthe operating mode of the hybrid power system 102. For example, thevehicle controller 202 may accept a gear-mode input operating signal, anaccelerator pedal depth input operating signal, brake pedal inputoperating signal, and a user-selected EV/HEV input operating signal, aswell as sensor input data, such as outside temperature, enginetemperature, vehicle speed, engine RPM, oil pressure, radiator watertemperature, and the like. The vehicle controller may utilize theabove-described input signals to control the torque and speed of thetraction motor 108.

Regarding certain input operating signals or parameters, the acceleratordepth input operating signal indicates the amount of depression of theaccelerator pedal by the driver. In one implementation, the acceleratordepth input operating signal indicates a depression percentage of theaccelerator pedal. In an alternative implementation, the acceleratordepth input operating signal indicates a depression distance of theaccelerator pedal. The accelerator depth input operating signal mayindicate a general or discrete amount of the accelerator pedal depth. Asexamples of measurements, the accelerator depth input operating signalmay indicate that the accelerator pedal is depressed 25%, 50%, 75%, oris depressed by any other number, whether whole or fractional. Theaccelerator depth input operating signal may also indicate a combinationof a depression percentage and a depression distance.

The brake input operating signal indicates the amount of depression of abrake pedal by the driver. In one implementation, the brake inputoperating signal indicates a depression distance that the brake pedal isdepressed. In another embodiment, the brake input operating signal mayindicate a depression percentage of the brake pedal. The brake inputoperating signal may indicate a combination of a depression percentageand a depression distance. In one embodiment, an angle sensor (notshown) in communication with the brake pedal communicates the brakeinput operating signal value to the vehicle controller. The brake inputoperating signal may be measured as a percentage, distance, or anysuitable unit of measurement.

The vehicle controller 202 may also accept and process other inputoperating signals, such as road surface gradient (hill angle), batterycapacity, vehicle velocity, or any other input signal. The surfacegradient input signal indicates the angle of the surface on which themotor vehicle is traveling. The vehicle controller 202 may use thesurface gradient input signal to control one or more components of thehybrid power system 102, such as the electric motor-generator 106 or theelectric traction motor 108, to prevent uncontrolled sliding of themotor vehicle during the ascent or descent on a sloping surface.

The battery capacity input status signal indicates the charge capacityof the battery pack 110. The measure of the charge capacity may be theamount of remaining charge of the battery pack 110 or may be the amountof total charge of the battery pack 110. For example, the batterycapacity input status signal may indicate that the battery pack 110 hasa 75% total charge. As another example, the battery capacity inputsignal may indicate that the battery pack 110 has a 25% remainingcharge.

The velocity input signal indicates the velocity of the motor vehicle.Based on the input operating signals and input status signals, thevehicle controller 202 outputs one or more output control signals tocontrol the vehicle. Examples of output control signals include a clutchengagement output signal that indicates whether the clutch 206 shouldengage or disengage, a starting power output signal that indicates theamount of starting power to start the engine 104, a target rotatingspeed output signal for the electric motor-generator 106, a targetrotating speed output signal for the electric traction motor 108, atarget rotating speed output signal for the engine 104, and a power ortorque indicator signal. The target rotating speed signals may be usedto synchronize the engine speed with the motor speeds when engaging theclutch.

The vehicle controller 202 may also communicate with the electricmotor-generator 106, the clutch controller 204, and the traction motor108. For example, the vehicle controller 202 may communicate the clutchengagement indicator output signal to the clutch controller 204.

The vehicle controller 102 may communicate with the engine 104, electricmotor-generator 106, and the traction motor 108 to form a subsystem tofacilitate charging the battery pack 110, directing power from thebattery pack 110, and for operating the driving wheels 212. In oneembodiment, the vehicle controller 102 may regulate a rotationaldifferential between the engine 104, the motor-generator 106, and thetraction motor 108 to facilitate engagement of the clutch 206. Inanother embodiment, the vehicle controller 102 may regulate a torquedifferential between the engine 104, the motor-generator 106, and thetraction motor 108 to facilitate disengagement of the clutch 206.

When the hybrid power system 102 is operating in the hybrid power mode,the vehicle controller 202 may determine a vehicle total power demandaccording to one or more input operating signals, input status signals,or combinations thereof. For example, the vehicle controller 202 maydetermine the vehicle total power demand using a throttle depth inputstatus signal, a velocity status input signal, or other signals. In oneimplementation, the vehicle controller 202 determines the total powerdemand based on a torque input status signal, a velocity input statussignal, and an accelerator depth input status signal. The total powerdemand signal may be used to determine the required power output of oneor more components, such as the engine 104, the motor-generator 106, andthe traction motor 108. The vehicle controller 202 may also use otheroperating power requirements, such as motor vehicle optimal operatingpower, to determine one or more of the required power outputs.

In one implementation, the vehicle controller 102 may determine thetraction motor 108 required power output by accounting for the bestpower output of the traction motor. One example for determining therequired power output of the traction motor 108 and the required poweroutput for the motor-generator 106 is shown below in the followingequations:1) If P−P _(e) ≦P ₂ _(—) _(MAX), then:if P−P _(e) <P2 _(—) _(MIN), then:P ₂ =P ₂ _(—) _(MAX) andP _(e) =P−P ₂, andP ₁=0;

-   -   Else then        P ₂ =P−P _(e) and        P ₁=0, and,        2) If P−P _(e) >P ₂ _(—) _(MAX), then        P ₂ =P ₂ _(—) _(MAX) and        P ₁ =P−P _(e) −P ₂, where:

P=the motor vehicle total power request,

P_(e)=the motor vehicle optimal operating power,

P₂ _(—) _(MAX)=the maximum power output of the traction motor,

P₂=the required power output of the traction motor, and

P₁=the required power output of the engine.

Although each of the operating modes are shown separately in FIGS. 3through 10, any operating mode may transition to another operating modeaccording to any combination of input operating signals, input statussignals, and output control signals. For example, the hybrid powersystem 102 may transition from the parallel power mode to theregenerative braking mode, or from the regenerative braking mode to thecharging power mode. Any other combinations of transitions are alsopossible depending on the state of the appropriate output signals andinput signals.

FIG. 36 shows one example of control system flow 3602 for controllingand/or changing the operating modes of a hybrid vehicle that employs thehybrid power system 102 and vehicle controller 202. In one embodiment,the vehicle controller 202 implements the control system flow 3602.

Initially, the vehicle controller 202 determines the present rank orgear mode of the hybrid motor vehicle. The present rank or gear mode maybe determined by the vehicle controller 202 in conjunction with the rankunit 1250. If the vehicle controller 202 determines that the presentgear-mode is a “park” gear-mode (3604), the vehicle controller 202instructs the hybrid power system 102 to cease operation or to halt(3606). For example, the vehicle controller 202 may instruct theinternal combustible engine 104, the electric motor-generator 106, andthe electric traction motor 108 to cease operation. The vehiclecontroller 202 may also instruct the torque distribution assembly 1802(clutch 206) to disengage.

If the vehicle controller 202 determines that the present gear-mode isnot the “park” gear-mode, the control system flow determines whether thehybrid motor vehicle is in a “neutral” gear-mode (3608). If the“neutral” gear-mode has been selected (3608), the vehicle controller 202may then determine if the user-selectable EV switch mode has beenselected (3610). Depending on whether the pure EV driving mode has beenselected, the control system flow compares the present battery pack 110capacity SOC against various threshold values.

If the electric-only power mode has been selected (3610), the vehiclecontroller 202 compares the present battery capacity SOC with anelectric-only minimum threshold SOC0 (3612). The electric-only minimumthreshold SOC0 may represent the minimum value of the battery pack 110discharging limit. For example, the electric-only minimum threshold SOC0may represent about a 10% to about a 15% remaining charge of the batterypack 110. Other values may be used, such as between about 5% and about20%. In another embodiment, if the electric-only power mode has beenselected, the vehicle will only operate in this selected mode if therequired driving power is less than about 90% of the maximum poweroutput of the traction motor 108. This value, for example, may rangefrom about 75% to about 95%.

If the present battery capacity SOC is greater than the electric-onlyminimum threshold SOC0 (3612), the control system flow sets theoperating mode of the hybrid power system 102 to electric-only powermode (3614). If the present battery capacity SOC is not greater than theelectric-only minimum threshold SOC0 (3612), the EV mode is released(3613). Control flow for setting the operating mode to electric-onlypower mode is explained with reference to FIG. 40 below.

If the electric-only power mode has not been selected (3610), thepresent battery capacity SOC is compared with an efficient operatingbattery threshold SOC2 (3616). The value of the efficient operatingbattery threshold SOC2 may represent about a 50% electric charge of thebattery pack 110. Other values may be used, such as between about 40%and about 60%. Battery capacity in the efficient operating batterythreshold SOC2 range indicates relatively efficient vehicle operation.If the present battery capacity SOC is greater than the efficientoperating battery threshold SOC2 (3616), the operating mode is set toelectric-only power mode operation (3614).

If the present battery capacity SOC is not greater than the efficientoperating battery threshold SOC2 (3616), the present battery capacitySOC is compared against a minimum electric starting capacity thresholdSOC1 (3618). For example, the minimum electric starting capacitythreshold SOC1 may represent a 30% electric charge of the battery pack110. Other values may be used, such as between about 20% and about 40%.Battery capacity above the minimum electric starting capacity thresholdSOC1 range indicates that sufficient battery power exists to start theengine 104. If the present battery capacity SOC is less than or equal tothe minimum electric starting capacity threshold SOC1 (3618), the seriesmode is set (3620). Control flow for setting the operating mode toseries mode operation (3620) is explained with reference to FIG. 41below.

The control system flow 3602 also considers a previous or existingoperating mode when determining a next operating mode. For example, whenthe present battery capacity SOC is not less than or equal to theminimum electric starting capacity threshold SOC1 (3618), and when theprevious operating mode was either in the series mode or the parallelmode (3622), the operating mode is set to series mode operation (3620).In step (3622), if the previous operating mode of the hybrid powersystem 102 was neither the series mode nor the parallel mode (3622), theoperating mode is set to electric-only power mode operation (3614).

If the vehicle is not in the “drive” gear-mode or the “reverse”gear-mode (3624), the control system flow assumes a neutral mode (3608).If “drive” or “reverse” gear mode has been selected (3624), controlsystem flow determines if an electric-only power mode has been selected(3626). If the present battery capacity SOC is not greater than theelectric-only minimum threshold SOC0 (3628), then the EV mode isreleased (3629), and control system flow determines if the presentbattery capacity SOC is greater than the efficient operating batterythreshold SOC2 (3630). If the present battery capacity SOC is greaterthan the efficient operating battery threshold SOC2 (3630), the controlsystem flow sets the operating mode of the hybrid power system 102 toelectric-only power mode (3614).

If the control system flow determines if the present battery capacitySOC is not less than or equal to the minimum electric starting capacitythreshold SOC1 (3632), the control system flow determines if theprevious operating mode was the series mode or the parallel mode (3634).If neither mode was previously selected, the control system flow setsthe operating mode of the hybrid power system 102 to electric-only powermode (3614).

Next, the vehicle controller 202 may evaluate the velocity of thevehicle relative to the present battery capacity, the previous operatingmodes, and/or other criteria. If the present velocity VELO is less thanthe lower velocity threshold VELO1, the operating mode is set to seriesmode (3620). In one implementation, the value of the lower velocitythreshold of the hybrid motor vehicle may be about 45 km/hr. This valuemay range, for example, between about 35 km/hr to about 55 km/hr.

Next, if the present velocity VELO is greater than the upper velocitythreshold VELO2 (3638), the operating mode is set to the parallel mode(3640). An example value for the upper velocity threshold VELO2 is about55 km/hr. Control flow for setting the operating mode to parallel modeoperation (3640) is explained with reference to FIG. 42. If the presentvelocity VELO is not greater than the upper velocity threshold VELO2(3638), the vehicle controller 202 determines whether the previousoperating mode was the series mode (3642). If the series mode waspreviously set (3642), the operating mode is then set to series mode(3620).

If the series mode was not previously set (3642), the vehicle controller202 determines whether the previous operating mode was the paralleloperating mode (3660). If the parallel mode was previously set (3660),the operating mode is then set to parallel mode (3640). If the parallelmode was not previously set (3660), the operating mode is then set toseries mode (3620).

FIG. 37 shows four graphs directed to engine and battery powerparameters, including a power charging graph 3702, an electric charging(ampere-hour) graph 3704, a velocity graph 3706, and a vehicle outputpower graph 3708. The power charging graph 3702 shows the power chargingaccording to different operating modes of the hybrid power system 102.The vertical axis is power measured in kilowatts, and the horizontalaxis represents the operating modes by letter segments. The powercharging graph 3702 shows a vehicle power demand graph 3710 and avehicle output power graph 3712. The vehicle output power graph 3708 issimilar to the power charging graph 3702, but only includes the vehicleoutput power line 3712.

The electric charging graph 3704 shows the electric charging rate of thebattery pack 110 according to different operating modes of the hybridpower system 102. The vertical axis is electric quantity measured inampere-hours (A-h), and the horizontal axis shows the operating modes.The line labeled SOC1 represents 30% of full battery charge, and theline SOC2 represents 50% of full battery charge, for example.

The velocity graph 3706 shows the velocity of the hybrid motor vehicleaccording to different operating modes of the hybrid power system 102.The vertical axis is velocity, and the horizontal axis represents theoperating mode. In one implementation, the line VELO1 represents thelower velocity threshold of 45 km/hr and the line VELO2 represents theupper velocity threshold of 55 km/hr.

According to FIG. 37, the operating modes of the hybrid vehicle may bedivided into 10 segments, labeled as A-K. The segments are approximateand may vary depending on the specific implementation of the hybridpower system 102. In one implementation, segments A-E represent theelectric-only power mode, segments E-F and I-K represent the seriespower mode, and the segments F-I represent the parallel mode.

In segments A-E, the hybrid power system 102 operates in theelectric-only power mode. In this mode, the clutch 206 is disengaged,the traction motor 108 is in operation, and the electric-motor generator106 and the internal combustible engine 104 are not operating.

In segments A-C, the vehicle is accelerating, which requires a positivetorque. Accordingly, in this region, the present battery capacity SOC isdecreasing and the battery pack 110 is supplying electricity to thetraction motor 108.

Segments C-D represent deceleration of the vehicle. During deceleration,the traction motor 108 uses regenerative braking and receives feedbacktorque from the driving wheels 212 to provide an electric charge to thebattery pack 110. Accordingly, in these segments, the present batterycapacity SOC is increasing.

Segments D-E represent a transition from the electric-only power mode tothe series hybrid mode, and the vehicle is accelerating. As the vehicleaccelerates, the hybrid power system 102 draws power from the batterypack 110. When the system approaches segment E, the present batterycapacity SOC is less than or equal to the electric starting batterycapacity threshold SOC1. As the system enters segment E region, ittransitions from the electric-only power mode to the series mode.

Segments E-F represent operation in the series mode. In these segments,the clutch 206 disengages, the traction motor 108 operates the drivingwheels 212, the engine 104 provides torque to the electricmotor-generator 106, while the electric motor-generator 106 provideselectricity to the traction motor 108. Since the hybrid vehicle isaccelerating in segments E-F and the power demands of the traction motor108 are greater than the electrical output of the electricmotor-generator 106, the traction motor 108 begins receiving electricityfrom the battery pack 110. Accordingly, the present battery capacity SOCdecreases in segments E-F regions.

Segment F represents a transition from the series mode to the parallelmode because the present velocity VELO of the vehicle meets and exceedsthe upper velocity threshold VELO2. Segments F-I represent the parallelmode. In these segments, the clutch 206 is engaged, and the engine 104,the electric motor-generator 106, and the electric traction motor 108operate the driving wheels 212. The present battery capacity SOCdecreases in segments F-G because the electric motor-generator 106 andelectric traction motor 108 require additional electricity from thebattery pack 110.

Segments G-H indicate that the vehicle requires a positive torque thatis less than the output of the engine 104. Because the torquerequirements of the vehicle are less than the torque output from theengine 104, the electric motor-generator 106 and the electric tractionmotor 108 operate to generate electricity from the surplus torque, whichis then supplied to the battery pack 110. Accordingly, segments G-H showthat the present battery capacity SOC is increasing.

Segments H-I indicate that the vehicle is decelerating and extra torqueis available. As the vehicle decelerates, the internal combustibleengine 104 and the traction motor 108 use surplus torque from the wheelsto generate electricity and charge the battery pack 110. Whileapproaching segment I, the operating mode transitions to the series modebecause the present battery capacity SOC is increasing, and the presentvelocity VELO is less than or equal to the lower velocity thresholdVELO1.

Segments I-K represent operation in the series mode. In these segments,the clutch 206 is disengaged and the traction motor 108 operates thedriving wheels 212. In addition, the engine 104 powers electricmotor-generator 106, which provides electricity to the battery pack 110.As the system approaches segment K, it transitions to the electric-onlypower mode because the present battery capacity SOC is greater than orequal to the efficient operating battery threshold SOC2. Alternatively,the hybrid power system 102 may operate according to the series modeuntil the electric-only power mode is selected.

FIG. 38 shows a graph 3802 comparing output torque with vehicle speedand shown how the torque changes as the speed of the respective engineor motor increases. Graph 3804 represents the output torque of themotor-generator 106, graph 3806 represents output torque of the tractionmotor 108, and graph 3808 represents the output torque of the engine104. Each graph represents the maximum output torque at different RPM,which is shown increasing along the horizontal axis.

When the engine 104 and/or motors 106, 108 are working, the outputtorque varies according to the vehicle demand. According to establishedengineering principles, power=torque×RPM×accelerator depth %. When thepower output reaches a maximum value, the rpm increases, but the torquedecreases. The data points 3816 on the graph 3802 indicate where thetorque begins to decrease at the maximum power output available, thus asRPM continues to increase, the torque decreases. The data points 3816shift along the horizontal axis for the different motors and the engine,respectively, because each device has a different maximum power.

This graph 3802 also explains why only a single drive gear ortransmission is needed. As mentioned above, only a single drive gear isneed to cover a large speed range, for example from zero km/hr to about160 km/hr. The traction motor 108 is used to bring the vehicle from astop to a cruising speed, whereas the engine 104 is not used at all atlow vehicle speeds. To accomplish this, the starting torque of thetraction motor 108 is very large, as shown by line 3806, and is muchgreater than the starting torque of the engine 104 (line 3808), thus thetransmission or gear reduction assembly 1108 does not need to provide alarge reduction ratio when compared to a conventional gas-enginevehicle.

Based on graph 3806 for the traction motor 108, only a single reductionratio for the traction motor 108 is needed to permit the traction motorto meet the torque demand over the range of RPM. Because the engine 104is not used to start vehicle, but rather is only used at high speeds, itcan power the vehicle in the hybrid parallel tri-power mode using thesame reduction ratio as used by the traction motor 108. For example, theengine 104 may be used above 4000 RPM to provide additional torque tothe wheels.

FIGS. 40-43 are flowcharts showing control in the operating modes, suchas the electric-only power mode, the series mode, and the parallel mode.The control flows shown in the flowcharts may be implemented by thevehicle controller 202, or other processing component of the system.

FIG. 40 shows electric-only power mode operation 4002. Initially, thecontrol flow determines whether the clutch 206 is disengaged (4004). Ifthe clutch is disengaged, the electrical power generating subsystem isinstructed to cease operation (4006). An example of an electrical powergenerating subsystem is the combination of the internal combustibleengine 104 and the electric motor-generator 106. Control flow thenverifies that the electric power generating subsystem has ceasedoperation (4008). When the electric power generating subsystem hasceased operation (4008), the operating mode is set to electric-onlypower mode (4010).

If the clutch is engaged (4004), control flow determines if the presentvelocity VELO exceeds an electric-only power mode velocity threshold(4012), such as VELO1 or VELO2. If the vehicle velocity VELO does notexceed the electric-only power mode velocity threshold, the clutch 206is disengaged (4014). However, if the present velocity VELO does exceedthe electric-only power mode velocity threshold, the electrical powergenerating subsystem is instructed to reduce its torque or mechanicaloutput (4016). The control flow may further determine if the presentelectric power output is less than or equal to an electric-only powermode electrical power output threshold (4018). In one implementation,the electric-only power mode electrical power output threshold is about5 kW.

FIG. 41 shows series mode operation (4102). Initially, the control flowdetermines if the clutch 206 is disengaged (4104). If it is disengaged,the electrical power generating subsystem is instructed to startoperation (4106). The control flow then verifies that the electric powergenerating subsystem has started operation (4108). When verified, theoperating mode is set to series mode (4110). When the clutch 206 is notdisengaged, control flow may then determine if the engine is rotating(4112). If the engine is not rotating, the clutch 206 is disengaged(4114). If the engine is rotating (4212), then the power output of thesubsystem is reduced (4116), and when it is less than about 5 kw (4118),the clutch is disengaged (4114).

FIG. 42 shows a parallel mode operation (4202). Initially, control flowdetermines if the clutch 206 is engaged (4204). If the clutch isengaged, the parallel mode is set (4206). If the clutch is disengaged,the electrical power generating subsystem is started (4208). The controlflow then verifies that the electric power generating subsystem hasstarted operation (4210). After verification, the difference in RPM (RPMdifferential) between the electric power generating subsystem and theelectric traction motor 108 is inspected (4212). In one implementation,the RPM differential between the electric power generating subsystem andthe electric traction motor 108 is compared with a parallel mode RPMdifferential threshold (4214). For example, the parallel hybrid mode RPMdifferential threshold may be about 200 RPM. When the RPM differentialbetween the electric power generating subsystem and the electrictraction motor 108 is less than or equal to the parallel mode RPMdifferential threshold, the clutch is engaged (4216).

FIG. 43 shows mode switching between the electric-only power mode, theseries mode, and the parallel mode (4302). Initially, an operating modeselection is detected (4304). Depending on the selected operating mode,control flow may pass to the electric-only power mode process 4002, theseries mode process 4102, or the parallel mode process 4202. Afterprocesses 4002, 4102, and 4202 have completed, the respective operatingmode, namely, the electric-only power mode (4306), the series mode(4308), or the parallel mode (4310) are indicated. Sub-modes andalternative operating modes are also possible.

FIG. 44 shows an electric schematic diagram 4402 that includes highpower/high current components, such as inverters and transistors, and/ordiscrete components. The transistors comprising the inverters may beinsulated gate bipolar transistors (IGBT), bipolar junction transistors(BJT) and/or high-power MOSFET devices. Other types of transistors maybe used. The inverters may be arranged as a three-phrase full bridgeinverter. The battery pack 110 is operatively coupled to a capacitorgroup 4404 and an inverter group 4406. The inverter group 4406 mayinclude three groups of two inverters, with each group corresponding toone phase of the traction motor 108. The inverter group 4406 is coupledto a driving isolation unit 4408, which optically isolates the highpower circuitry from the digital electronics portion, such as a motorcontroller 4410. The driving isolation unit 4408 may communicate withthe motor controller 4410 using pulse width modulation (PCM) signals,which essentially control the duty cycle and on-off state of inverters.

The output of each of the inverter groups 4406 is coupled to an inputwinding (U, V, W) of the electric traction motor 108. The electrictraction motor 108 is in turn coupled to a rotary transformer 4412. Inone embodiment, the electric traction motor 108 is a Wye-connectedthree-phase motor. However, other types of motor connections may beused, such as a delta-connection, a split-phase connection, and thelike. The rotary transformer 4412 monitors the rotor of the electrictraction motor 108 and communicates the position of the rotor to themotor controller 4410.

Note that the vehicle controller 202 and/or motor controller 4402 arenot limited to the embodiments described in this document. The vehiclecontroller 202 and/or the motor controller 4410, may include additionalor different logic and may be implemented in many different ways. Suchcontrollers may be implemented as a microprocessor, microcontroller,application specific integrated circuit (ASIC), discrete logic, or acombination of other types of circuits or logic. Similarly, thecontrollers may include various memory devices, such as, DRAM, SRAM,Flash, or other types of memory. Parameters (e.g., conditions andthresholds) and other data structures may be separately stored andmanaged, may be incorporated into a single memory or database, or may belogically and physically organized in many different ways. Programs andinstruction sets may be parts of a single program, separate programs, ordistributed across several memories and processors.

The logic may be represented in (e.g., stored on or in) acomputer-readable medium, machine-readable medium, propagated-signalmedium, and/or signal-bearing medium. The media may comprise any devicethat contains, stores, communicates, propagates, or transportsexecutable instructions for use by or in connection with an instructionexecutable system, apparatus, or device. The machine-readable medium mayselectively be, but is not limited to, an electronic, magnetic, optical,electromagnetic, or infrared signal or a semiconductor system,apparatus, device, or propagation medium. A non-exhaustive list ofexamples of a machine-readable medium includes: a magnetic or opticaldisk, a volatile memory such as a Random Access Memory “RAM,” aRead-Only Memory “ROM,” an Erasable Programmable Read-Only Memory (i.e.,EPROM) or Flash memory, or an optical fiber. A machine-readable mediummay also include a tangible medium upon which executable instructionsare printed, as the logic may be electronically stored as an image or inanother format (e.g., through an optical scan), then compiled, and/orinterpreted or otherwise processed. The processed medium may then bestored in a computer and/or machine memory.

While various embodiments of the invention have been described, it willbe apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible within the scope of theinvention. Accordingly, the invention is not to be restricted except inlight of the attached claims and their equivalents.

We claim:
 1. A control system for controlling operating modes of ahybrid vehicle, the vehicle comprising: an internal combustion engine; afirst electric motor-generator; an electric traction motor; a batterypack; a clutch physically disposed between the engine and the firstelectric motor-generator and configured to selectively engage anddisengage the engine from the traction motor; and a user-selectableswitch configured to permit an operator to select an electric-only powermode and override a hybrid driving mode; and the control systemcomprising: a vehicle controller operative to: receive a gear modeindicator, an electric-only power mode indicator, and a present batterystorage capacity; compare the present battery storage capacity with abattery threshold; select an operating mode based on the gear-modeindicator, the electric-only power mode indicator, and a result of thecomparison; and output a selected operating mode to control the engine,the first electric motor-generator, and the electric traction motor, sothat the vehicle operates according to the selected mode.
 2. The controlsystem of claim 1, wherein: the battery threshold is an electric-onlyminimum battery threshold; and the vehicle controller selects theelectric-only power mode as an operating mode when: the gear-modeindicator indicates either a neutral, a drive, or a reverse gear-mode;the electric-only power mode indicator indicates that the electric-onlypower mode has been selected; and the present battery storage capacityis greater than the electric-only minimum battery threshold.
 3. Thecontrol system of claim 1, wherein: the battery threshold is a minimumelectric starting capacity threshold; and the vehicle controller isfurther operative to: compare the present battery storage capacity withthe minimum electric starting capacity threshold; determine a previousoperating mode of the vehicle; and select an operating mode based on thecomparison between the present battery storage capacity and the minimumelectric starting capacity threshold, and the determined previousoperating mode.
 4. The control system of claim 3, wherein the vehiclecontroller selects an electric-only power mode as the operating mode. 5.The control system of claim 3, wherein the vehicle controller selects aseries mode as the operating mode.
 6. The control system of claim 3,wherein: the vehicle controller is further operative to: compare thepresent battery storage capacity with an efficient operating batterythreshold; and select the series mode as the operating mode when: thegear-mode indicator indicates a drive or a reverse gear-mode; theelectric-only power mode indicator indicates that the electric-onlypower mode is not selected; the present battery storage capacity is notgreater than the efficient operating battery threshold; and the presentbattery storage capacity is less than the minimum electric startingcapacity threshold.
 7. The control system of claim 6, wherein theselected series mode is a series dual-power mode.
 8. The control systemof claim 1, wherein the vehicle controller is further operative to:receive a velocity input signal that indicates a velocity of the hybridvehicle; compare a value of the velocity input signal with an uppervelocity threshold; and further select the operating mode of the vehiclebased on the comparison of the value of the velocity input signal withthe upper velocity threshold.
 9. The control system of claim 8, wherein:the battery threshold is an efficient operating battery threshold; andthe vehicle controller selects a parallel tri-power mode as theoperating mode when: the gear-mode of the hybrid vehicle is a drive orreverse gear-mode; the electric-only power mode selection indicates thatthe electric-only power mode has not been selected; the present batterystorage capacity is not greater than the efficient operating batterythreshold; and the value of the velocity input signal is greater thanthe upper velocity threshold.
 10. The control system of claim 1, whereinthe vehicle controller is further operative to: receive a velocity inputsignal that indicates the velocity of the hybrid vehicle; receive alower velocity threshold; determine a previous operating mode of thevehicle; and further select the operating mode of the vehicle based on acomparison of a value of the velocity input signal with the lowervelocity threshold, and the determined previous operating mode.
 11. Thecontrol system of claim 10, wherein: the battery threshold is anefficient operating battery threshold; and the vehicle controllerselects a series mode as the operating mode when: the gear-mode of thehybrid vehicle is a drive or reverse gear-mode; the electric-only powermode selection indicates that the electric-only power mode has not beenselected; a comparison of the present battery storage capacity and theefficient operating battery threshold indicates that the present batterystorage capacity is less than the efficient operating battery capacitythreshold; the determined previous operating mode of the hybrid powersystem is a parallel tri-power mode; and the value of the velocity inputsignal is less than the lower velocity threshold.
 12. The control systemof claim 10, wherein: the battery threshold is an efficient operatingbattery threshold; and, the vehicle controller selects a paralleltri-power mode as the operating mode when: the gear-mode indicator ofthe vehicle indicates a drive or reverse gear-mode; the electric-onlypower mode selection indicates that the electric-only power mode has notbeen selected; the present battery storage capacity is not greater thanthe efficient operating battery threshold; the determined previousoperating mode is the series hybrid mode; and the value of the velocityinput signal is greater than the upper velocity threshold.
 13. Thecontrol system of claim 1, where the operating mode of the vehicle isselected from an operating mode group comprising: the electric-onlypower mode defined by operating the fraction motor to provide torque toa set of driving wheels using power supplied solely by the battery packin communication with the traction motor; a series mode defined byoperating the traction motor to provide torque to the set of drivingwheels using power supplied by the motor-generator in communication withthe traction motor, wherein excess power generated by themotor-generator is provided to charge the battery pack; a seriesdual-power mode defined by operating the traction motor to providetorque to the set of driving wheels using power supplied by themotor-generator and power supplied by the battery pack; a paralleldual-power mode defined by operating the traction motor to providetorque to the set of driving wheels using power supplied by the batterypack, and by operating the internal combustion engine to provideadditional torque, wherein excess power generated by the motor-generatoris provided to charge the battery pack; and a parallel tri-power modedefined by operating the traction motor and the motor-generator toprovide torque to the set of driving wheels using power supplied by thebattery pack, and by operating the internal combustion engine to provideadditional torque.
 14. A method for controlling operating modes of ahybrid vehicle, the vehicle having: an internal combustion engine; afirst electric motor-generator; an electric traction motors; a batterypack; a clutch physically disposed between the engine and the firstelectric motor-generator and configured to selectively engage anddisengage the engine from the traction motor; and a user-selectableswitch configured to permit an operator to select an electric-only powermode and override a hybrid driving modes; the method comprising:receiving a gear mode indicator, an electric-only power mode indicator,and a present battery storage capacity; comparing the present batterystorage capacity with a battery threshold; selecting an operating modebased on the gear-mode indicator, the electric-only power modeindicator, and a result of the comparison; and selecting an operatingmode to control the engine, the first electric motor-generator, and theelectric traction motor, so that the vehicle operates according to theselected mode.